1. Field of the Invention
The invention relates to a bone transfixion plate for transfixing an acetabulum fragment of the os ilium to the os ilium following a hip osteotomy with rotation of the roof of the acetabulum, in a human patient, wherein a section is performed on the acetabulum in the region of the os ilium and os ischium, which section may employ a single common cut, particularly a cut which is essentially along a cylindrical surface, and a second section is performed in the region of the os pubis, employing a cut which may particularly be planar, and wherewith the plate is affixed stably to the facies glutea of the cranial pelvic column of the ala ossis ilii.
2. Description of the Prior Art
There are various techniques of double and triple osteotomy for hip socket rotation in treating hip joint dysplasia, particularly in human medicine. The one considered most successful is a triple osteotomy wherein the section of the acetabulum is approximately spherical, the advantage being that the acetabulum can then be shifted laterally as well as ventrally. For this triple technique, sections must be performed on the os ilium, os ischium, and os pubis.
First the ischial osteotomy is performed, with a section from the foramen ischiadicum to the foramen obturatum; the os ischium then remains held dorsally by ligaments which connect to the tuber ischii and spina ischiadica, and other ligaments which pull toward the sacrum. It should be noted in this connection that the foramen obturatum is involved, and because of the condition that the os ischium must be sharply resected to the membrana obturata, strips of bone which are formed must be sectioned in order to be able to eventually rotate the acetabulum.
Then the osteotomy of the os pubis is performed, close to the hip joint. The line of the osteotomy is parallel to the acetabulum, at a slight inclination into the foramen obturatum, in order to ensure some bone contact following the acetabulum rotation, thereby facilitating rapid bone healing.
The third stage is the osteotomy of the os ilium. A Steinmann pin is inserted in advance into the pelvic bone to assist later on in rotating and swinging the acetabulum parallel to the planned osteotomy which is inclined medially. The iliac osteotomy is planar, performed first with an oscillating saw and then with chisels.
Following the osteotomies, the acetabulum is then rotated and swung, over the head of the femur, with the extent of such rotation and swinging being at least based on the need prior to the surgery to brace the head of the femur in order for it to come under the roof of the acetabulum. For this purpose, the roof of the acetabulum is pulled over the head of the femur on a Steinmann pin, and where required is also pulled forward, and the medial ramus of the os pubis is also pressed so as to rotate upward. Then the acetabulum is urged medially by manual force, and a good contact of the acetabulum fragment with the os pubis is created.
There should be substantial superposition by the sclerosing zone of the roof of the acetabulum and by the facies lunata, to become disposed over the head of the femur, because this creates the proper surface for receiving and transmitting compressive forces generated by stresses from the leg. The subsequent transfixion of the acetabulum is by Kirschner wires inserted into the acetabulum fragment in four different directions, with the far ends of said wires being pinched off and bent around on the crest of the ilium. This type of transfixion is difficult, often unstable, and often leads to an unsatisfactory outcome, wherein the acetabulum is not firm, the healing of bone is sharply retarded, and the patient must spend many weeks bedridden in a trunk-pelvis cast.
A basic reason for these problems is the unstable fixation achieved by Kirschner wires which are, however, necessary. A major reason why Kirschner wires are needed is that the iliac osteotomy is planar, wherewith when the acetabulum is swung ventrally and laterally an open wedge-shaped gap is created between the ala ossis ilii and the acetabulum fragment, and as a rule this gap must be filled by a wedge of bone which is sawed out of the crest of the ilium and is implanted in said gap; and accordingly the resulting three-body system must be transfixed and also must be amenable to new bone growth.
In a completely different technical context from this invention, a bone plate applicable in the acetabulum region is disclosed in Ger. AS No. 24 10 057, for forming an artificial border for the roof of the acetabulum without otherwise modifying the hip joint, in particular without performing an osteotomy on the hip bone (os coxae). This known plate is fixed to the os ilium by two proximal lug strips with a recess between them for accommodating the base of the crest of the ilium. The plate rests on the roof of the acetabulum, and the distal region of the plate, which is bent-in ventrally, forms the border of the roof of the acetabulum. In other words, the proximal region of the acetabulum (the "roof" of the acetabulum) is widened, primarily in the lateral direction, in order to prevent luxation of the head of the femur in the proximal direction. The purpose of this known plate, and accordingly its geometric configuration, are completely different from those of the plate of the instant invention.